Biopsy apparatus and biopsy method

ABSTRACT

A biopsy apparatus has a biopsy needle, which faces a radiation reception surface of a radiation detector and is held obliquely to the radiation reception surface by a biopsy needle holding mechanism. The biopsy apparatus includes a radiographic image capturing apparatus for capturing two radiographic images. One of the two radiographic images is produced according to a scout image capturing mode or a stereographic image capturing mode, and the other is produced according to the stereographic image capturing mode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromPatent Application No. 2009-085879 filed on Mar. 31, 2009, in the JapanPatent Office, of which the contents are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a biopsy apparatus and a biopsy methodfor calculating a three-dimensional position of a region to be biopsied(hereinafter referred to as a “biopsy region”) of an object to beexamined, based on at least two radiographic images obtained byirradiating the object with radiation from directions that are differentfrom each other, then moving a biopsy needle to the biopsy region basedon the calculated three-dimensional position, and removing a tissuesample from the biopsy region.

2. Description of the Related Art

Heretofore, biopsy apparatus have been developed in the art for removinga tissue sample from a biopsy region of an object to be examined (e.g.,an inflicted region of a breast of a subject) and examining the tissuesample to perform a disease diagnosis of the subject. In order toidentify the position of the biopsy region, the biopsy apparatusincorporates a radiographic image capturing apparatus, which captures aplurality of radiographic images under a stereographic image capturingmode by applying radiation to the object from directions that aredifferent from each other. The three-dimensional position of the biopsyregion is specified using the captured radiographic images. Then, abiopsy needle is moved toward the biopsy region based on the specifiedthree-dimensional position, and a tissue sample is removed from thebiopsy region.

Techniques for specifying the position of a biopsy region using aplurality of radiographic images, techniques for removing a tissuesample from the biopsy region, and techniques concerning radiographicimage capturing apparatus incorporated in biopsy apparatus have beenproposed or disclosed in Japanese Patent No. 3668741, Japanese Laid-OpenPatent Publication No. 2001-504002 (PCT), Japanese Laid-Open PatentPublication No. 10-201749, and Japanese Laid-Open Patent Publication No.2002-186623.

It is proposed in Japanese Patent No. 3668741 that a scintillator of aradiation detector converts radiation into light, and that a CCD arrayconverts the light into a radiation image.

It is proposed in Japanese Laid-Open Patent Publication No. 2001-504002(PCT) that the cassette of a radiation detector is separated from aradiographic image capturing apparatus when the cassette is not in use.

It is proposed in Japanese Laid-Open Patent Publication No. 10-201749 toacquire two radiographic images by irradiating a phantom having amarker, which is disposed in a known position, with radiation at twoangles, whereby a calculating algorithm for identifying the position ofa biopsy region is modified based on the acquired two radiographicimages and the position of the marker of the phantom.

Japanese Laid-Open Patent Publication No. 2002-186623 discloses that abiopsy needle is inserted obliquely into a biopsy region in order toremove sample tissue therefrom.

In a stereographic image capturing mode that applies radiation to anobject from different directions, since plural radiographic images needto be captured in order to identify the position of the biopsy region,the dose of radiation applied to the examinee is increased. Further, thetime required to examine the biopsy region depends on the skill of thedoctor or technician who uses the biopsy apparatus. Therefore, if thedoctor or technician who uses the biopsy apparatus is not skilled, thenthe examination process becomes time-consuming, and tends to hold theobject for a long period of time. Consequently, it would be desirable toreduce the number of radiographic images that are captured, for therebyminimizing the dose of applied radiation and shortening the timerequired for the examination process.

According to Japanese Patent No. 3668741, since a CCD array is used tocapture a radiographic image of an object, the object is exposed toradiation at all times, and hence the applied radiation dose is high.According to Japanese Laid-Open Patent Publication No. 2001-504002(PCT), since eight to ten radiographic images need to be captured inorder to identify the position of the biopsy region, the number ofcaptured radiographic images cannot be reduced, and further, the appliedradiation dose cannot be reduced. Japanese Laid-Open Patent PublicationNo. 10-201749 and Japanese Laid-Open Patent Publication No. 2002-186623do not propose any techniques or methods aimed at reducing the number ofradiographic images required to be captured so as to reduce the appliedradiation dose. In addition, attempts to shorten the time required forthe examination process by reducing the number of captured radiographicimages have not been proposed in Japanese Patent No. 3668741, JapaneseLaid-Open Patent Publication No. 2001-504002 (PCT), Japanese Laid-OpenPatent Publication No. 10-201749, or Japanese Laid-Open PatentPublication No. 2002-186623.

Japanese Laid-Open Patent Publication No. 2001-504002 (PCT) disclosesthat the angle of a radiation source with respect to the perpendicularaxis of a radiation reception surface of the radiation detector is setto ±15° in a stereographic image capturing mode. The angle of theradiation source is set this way because if a scout image capturing modeis performed to irradiate the object with radiation emitted from aradiation source disposed on the perpendicular axis (0°), then thebiopsy needle also is imaged in overlapping relation to the biopsyregion in the radiographic image captured in the scout image capturingmode, thus making it impossible to identify the position of the biopsyregion. According to Japanese Laid-Open Patent Publication No.2001-504002 (PCT), in order to prevent the biopsy needle from beingimaged, the biopsy region is imaged while capturing two radiationimages, i.e., when the radiation source is positioned at an angle of+15° and an angle of −15° respectively, whereby the position of thebiopsy region is identified using the two captured radiographic images.

In the scout image capturing mode, scattered rays of radiation, whichare generated when radiation is applied to the object, are removed by agrid. The grid is of a structure having an alternate pattern made up ofone material, which is permeable to radiation, and another material,which absorbs radiation. The grid is disposed near the radiationreception surface of the radiation detector. In the stereographic imagecapturing mode, since the angle of the radiation source with respect tothe perpendicular axis of the radiation reception surface of theradiation detector is set to ±15°, which differs from the angle of theradiation source used in the scout image capturing mode, the radiationrequired to capture radiation images tends to be absorbed by the grid.Consequently, the grid cannot be used in the stereographic imagecapturing mode. As a result, radiation images captured in thestereographic image capturing mode may possibly be of low quality, dueto such scattered radiation.

SUMMARY OF THE INVENTION

It is an object of the present invention to reduce the number ofradiographic images to be captured of an object and to reduce theradiation dose applied to the object to capture radiographic images,while also shortening the time required to examine the object.

Another object of the present invention is to produce radiographicimages of high quality.

To achieve the above objects, there is provided in accordance with thepresent invention a biopsy apparatus comprising a radiographic imagecapturing apparatus including a radiation source for applying radiationto an object to be examined, and a radiation detector for detecting theradiation which has passed through the object and converting thedetected radiation into a radiographic image, and a biopsy needlepositioning device including a biopsy region positional informationcalculator for calculating a three-dimensional position of a biopsyregion of the object based on at least two radiographic images obtainedby irradiating the object with the radiation from directions that aredifferent from each other, a biopsy needle for piercing the biopsyregion based on the calculated three-dimensional position of the biopsyregion and sampling tissue of the biopsy region, and a biopsy needleholding mechanism for holding the biopsy needle, wherein the biopsyneedle faces a radiation reception surface of the radiation detector andis held obliquely to the radiation reception surface by the biopsyneedle holding mechanism, wherein one of the at least two radiographicimages comprises either a radiographic image produced according to ascout image capturing mode, in which the object is irradiated with theradiation applied from the radiation source when the radiation source isdisposed on an axis perpendicular to the radiation reception surface, ora radiographic image produced according to a stereographic imagecapturing mode, in which the object is irradiated with the radiationapplied from the radiation source when the radiation source is disposedobliquely to the axis, and wherein the other of the at least tworadiographic images comprises a radiographic image produced according tothe stereographic image capturing mode.

According to the present invention, there also is provided a biopsymethod comprising the steps of detecting radiation applied from aradiation source and having passed through an object to be examined, andconverting the detected radiation into at least two radiation imageswith a radiation detector having a radiation reception surface, the tworadiation images being produced either according to a scout imagecapturing mode, in which the object is irradiated with radiation appliedfrom the radiation source when the radiation source is disposed on anaxis perpendicular to the radiation reception surface, and astereographic image capturing mode, in which the object is irradiatedwith the radiation applied from the radiation source when the radiationsource is disposed obliquely to the axis, or according to thestereographic image capturing mode, calculating a three-dimensionalposition of a biopsy region of the object based on the at least tworadiographic images with a biopsy region positional informationcalculator, and piercing the biopsy region with a biopsy needle based onthe calculated three-dimensional position of the biopsy region andsampling tissue of the biopsy region while the biopsy needle faces theradiation reception surface and is held obliquely to the radiationreception surface by a biopsy needle holding mechanism.

Since the biopsy needle is held obliquely to the radiation receptionsurface of the radiation detector, the biopsy needle is reliablyprevented from overlapping the biopsy region in the radiographic imageproduced in the scout image capturing mode. Therefore, the radiographicimage produced in the scout image capturing mode can also be used as aradiographic image for identifying the three-dimensional position of thebiopsy region. In other words, the three-dimensional position of thebiopsy region can be identified using two radiographic images, one ofwhich is produced in the scout image capturing mode and the other ofwhich is produced in the stereographic image capturing mode.

For identifying the position of the biopsy region, it heretofore hasbeen customary to perform the scout image capturing mode, confirm thatthe object is included in the radiographic image produced in the scoutimage capturing mode, thereafter move the radiation source from theimaging angle in the scout image capturing mode in order to capture afirst radiographic image in the stereographic image capturing mode, thenmove the radiation source again from the imaging angle in thestereographic image capturing mode to another imaging angle in order tocapture a second radiographic image in the stereographic image capturingmode, and subsequently identify the three-dimensional position of thebiopsy region using the two radiographic images produced at respectiveimaging angles in the stereographic image capturing mode. Since it takestime to move the radiation source between the image capturing modes, theexamination time cannot be shortened.

According to the present invention, as described above, since theradiographic image produced in the scout image capturing mode also isused as a radiographic image for identifying the three-dimensionalposition of the biopsy region, a second radiographic image, whichheretofore has been produced in the stereographic image capturing mode,no longer is required. Rather, the three-dimensional position of theobject can be identified using the radiographic image produced in thescout image capturing mode together with the first radiographic imageproduced in the stereographic image capturing mode. As a result, thenumber of captured radiographic images is reduced, and hence the dose ofradiation applied to the breast also is reduced. Inasmuch as the numberof captured radiographic images is reduced, the time required to movethe radiation source between image capturing modes also is shortened.Therefore, the time required to examine the biopsy region can beshortened, and the object does not need to be held for a long period oftime.

Furthermore, since a grid is used in the scout image capturing mode, theradiographic image produced in the scout image capturing mode is ofhigher quality than the radiographic image produced in the stereographicimage capturing mode. Accordingly, a radiographic image of high qualitycan be used to identify the three-dimensional position of the biopsyregion. In other words, the three-dimensional position of the biopsyregion can be identified with high accuracy using both the radiographicimage of high quality and the first radiographic image produced in thestereographic image capturing mode.

According to the present invention, since two radiographic images can beproduced in the stereographic image capturing mode, in addition to tworadiographic images produced respectively in the scout image capturingmode and the stereographic image capturing mode, the present inventioncan easily be applied to existing biopsy apparatus.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a biopsy apparatus according to anembodiment of the present invention;

FIG. 2 is a fragmentary perspective view of the biopsy apparatus shownin FIG. 1;

FIG. 3 is a fragmentary side elevational view of the biopsy apparatusshown in FIG. 1;

FIG. 4 is a schematic view illustrating a scout image capturing mode;

FIG. 5 is a schematic view illustrating the scout image capturing modeand a stereographic image capturing mode;

FIG. 6 is a schematic view illustrating the scout image capturing modeand the stereographic image capturing mode;

FIG. 7 is a schematic view illustrating the stereographic imagecapturing mode;

FIG. 8 is a schematic view illustrating the scout image capturing modeand the stereographic image capturing mode;

FIG. 9 is a schematic view illustrating the scout image capturing modeand the stereographic image capturing mode;

FIG. 10 is a schematic view illustrating the stereographic imagecapturing mode;

FIG. 11 is a block diagram of the biopsy apparatus shown in FIG. 1; and

FIG. 12 is a flowchart of an operation sequence carried out by thebiopsy apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A biopsy apparatus according to a preferred embodiment of the presentinvention will be described below in relation to a biopsy method withreference to the drawings.

As shown in FIGS. 1 through 3, a biopsy apparatus 10 according to anembodiment of the present invention includes a bed 14 on which anexaminee (subject) 12 lies. The bed 14 comprises a base 16, upstandingsupport members 18, 20 mounted on the base 16, and a top plate 22supported on the support members 18, 20. The top plate 22 has an opening28 defined therein for a breast (an object to be examined) 26 of theexaminee 12. The breast hangs down through the opening when the examinee12 lies on the top plate 22 with the chest wall 24 of the examinee 12facing downward.

A support arm 32 is movably mounted on a side surface of the supportmember 20 for movement along a rail 30, which is attached to the supportmember 20 and extends vertically in the directions indicated by thearrow x. The support arm 32 has a distal end 34 from which a shaft 36extends upwardly. An arm 40 has a proximal end 38 pivotally supported onthe distal end 34, and a distal end to which there is fixed a radiationsource casing 44 housing a radiation source 42 therein for emittingradiation 92 (see FIG. 4). The arm 40 is angularly movable about theshaft 36 in horizontal directions, within a plane that includes thedirections indicated by the arrows y and z.

The shaft 36 supports on its upper distal end a support member 46, whichsupports thereon an image capturing base 52 housing therein a grid 48for removing scattered rays of radiation 92 applied from the radiationsource 42 to the breast 26, and a solid-state detector (radiationdetector) 50 for detecting radiation 92 that has passed through thebreast 26.

A guide rail 54 extends from a side surface of the support member 46along an axis (indicated by the arrow z) perpendicular to the surface ofthe image capturing base 52 (the grid 48 and the solid-state detector50). The guide rail 54 has a groove 56 defined therein, which extendsalong the directions indicated by the arrow z.

A support member 62, which is movable along the groove 56, is movablymounted on the guide rail 54. A compression plate 58 for compressing andholding the breast against the image capturing base 52 is mounted on thesupport member 62 by a support member 64.

Another support member 66, which is movable along the groove 56, ismovably mounted on the guide rail 54 closer to the radiation sourcecasing 44 than the support member 62.

The support member 66 is substantially L shaped as viewed in sideelevation, and has a vertical guide rail 68 on which a slide member 70is vertically movably supported.

The slide member 70 has a guide rail 72 disposed on the upper surfacethereof, extending in the directions indicated by the arrow y. A slidemember 74 is slidably mounted on the guide rail 72 for sliding movementalong the guide rail 72 in the directions indicated by the arrow y. Theslide member 74 has a support member 76 mounted on an upper surfacethereof, and the support member 76 includes a shaft 78 extending in thedirections indicated by the arrow y. A support member 82 is pivotallysupported on the shaft 78, and a holster 80 including a biopsy needle 86mounted thereon is attached to the support member 82.

The biopsy needle 86 pierces a biopsy region 88 (e.g., a calcifiedregion) of the breast 26, which has been compressed between thecompression plate 58 and the image capturing base 52, through an opening84 defined in the compression plate 58. The biopsy needle 86 has asampler 90 for drawing and sampling a tissue portion from the biopsyregion 88.

The holster 80 serves as a manipulator for manipulating the biopsyneedle 86. For example, the holster 80 causes the biopsy needle 86 topierce the biopsy region 88, causes the sampler 90 to draw a tissueportion from the biopsy region 88, and pulls the biopsy needle 86 outfrom the breast 26 after the tissue portion has been sampled by thesampler 90.

The biopsy needle 86 can be displaced in directions indicated by thearrow z when the support member 66 moves along the groove 56. The biopsyneedle 86 can be displaced in directions indicated by the arrow x whenthe slide member 70 moves along the guide rail 68. The biopsy needle 86can be displaced in directions indicated by the arrow y when the slidemember 74 moves along the guide rail 72. The biopsy needle 86 can beturned about the shaft 78 when the support member 82 and the holster 80are turned about the shaft 78.

The support members 66, 76, 82, the guide rails 68, 72, the slidemembers 70, 74, the shaft 78, and the holster 80 collectively make up abiopsy needle holding mechanism 60 for holding the biopsy needle 86.

In FIG. 3, the biopsy needle 86 is inclined at an angle φ with respectto an axis (in directions indicated by the arrow z) perpendicular to theradiation reception surface (closer to the breast 26) of the solid-statedetector 50. Therefore, the biopsy needle 86 obliquely pierces thebiopsy region 88 for sampling a tissue portion of the biopsy region 88.The angle φ is in a range 0°<φ≦10°.

The arm 40, the radiation source casing 44 housing the radiation source42, the support members 46, 62, 64, the image capturing base 52 housingthe grid 48 and the solid-state detector 50, the guide rail 54, and thecompression plate 58 collectively make up a radiographic image capturingapparatus (breast image capturing apparatus) 94.

An image capturing process performed by the radiographic image capturingapparatus 94 (biopsy apparatus 10) will be described below withreference to FIGS. 4 through 10.

The radiographic image capturing apparatus 94 performs a scout imagecapturing mode (see FIGS. 4 through 6), in which the breast 26 isirradiated with radiation 92 emitted from the radiation source 42, whichis disposed on an axis perpendicular to the radiation reception surfaceof the solid-state detector 50, i.e., the directions indicated by thearrow z perpendicular to the surface of the solid-state detector 50,which is located closer to the breast 26. Alternatively, theradiographic image capturing apparatus 94 performs a stereographic imagecapturing mode (see FIGS. 5 through 10), in which the breast 26 isirradiated with radiation 92 emitted from the radiation source 42, whichis disposed obliquely to the axis perpendicular to the radiationreception surface of the solid-state detector 50. The solid-statedetector 50 detects radiation 92 that has passed through the breast 26in the scout image capturing mode or the stereographic image capturingmode, and converts the detected radiation 92 into a radiographic image.

More specifically, the radiographic image capturing apparatus 94captures radiographic images of the breast 26 according to either one ofthe image capturing processes shown in FIGS. 4 through 10.

FIG. 4 shows an image capturing process for capturing a radiographicimage in the scout image capturing mode. In this image capturingprocess, since scattered rays of radiation 92 are removed by the grid48, the solid-state detector 50 can output a radiographic image of highquality, which is free from the effect of scattered rays. In FIG. 4, theangle θ of the radiation source 42 with respect to the radiationreception surface of the solid-state detector 50 is θ=0°. The positionof the radiation source 42 in the scout image capturing mode is referredto as “position A”.

FIG. 5 shows an image capturing process for capturing a radiographicimage in the scout image capturing mode together with capturing aradiographic image in the stereographic image capturing mode with theradiation source 42 placed in a position B, which is angularly spaced atan imaging angle +θ1 (+θ1≦10°) from the position A. At the imaging angle+θ1 (the position B), the radiation source 42 is not significantlyinclined from the position A. Therefore, even if the grid 48 is used inthe stereographic image capturing mode, the possibility that radiation92 will be removed by the grid 48 is small. Consequently, thesolid-state detector 50 can output two radiographic images of highquality, which are free from the effect of scattered rays. In FIG. 5,the scout image capturing mode and the stereographic image capturingmode may be performed in any desired order. The radiation source 42 canbe moved between position A and position B by turning the arm 40 aboutthe shaft 36.

FIG. 6 shows an image capturing process for capturing a radiographicimage in the scout image capturing mode together with capturing aradiographic image in the stereographic image capturing mode with theradiation source 42 placed in a position C, which is angularly spaced atan imaging angle −θ1 (|−θ1|≦10°) from the position A. At the imagingangle −θ1 (the position C), the radiation source 42 is not significantlyinclined from the position A, similar to the position B shown in FIG. 5.Therefore, even if the grid 48 is used in the stereographic imagecapturing mode, the possibility that radiation 92 will be removed by thegrid 48 is small. Consequently, the solid-state detector 50 can outputtwo radiographic images of high quality, which are free from the effectof scattered rays.

FIG. 7 shows an image capturing process for capturing radiographicimages in the stereographic image capturing mode with the radiationsource 42 placed in respective positions B, C, which are angularlyspaced at respective imaging angles +θ1, −θ1 from the position A.According to this image capturing process, the solid-state detector 50can output two radiographic images of high quality, which are free fromthe effect of scattered rays, similar to the image capturing processesshown in FIGS. 5 and 6.

FIG. 8 shows an image capturing process for capturing a radiographicimage in the scout image capturing mode (see FIG. 4) together withcapturing a radiographic image in the stereographic image capturing modewith the radiation source 42 placed in a position D, which is angularlyspaced at an imaging angle +θ2 (+θ2≦+30° and +θ2>+θ1) from the positionA. At the imaging angle +θ2 (position D), the radiation source 42 isinclined from the position A more greatly than in the position B (seeFIG. 5). Therefore, if the grid 48 is used in the stereographic imagecapturing mode, radiation 92 possibly will be removed by the grid 48.Consequently, in position D, the grid 48 is not used in thestereographic image capturing mode. The solid-state detector 50 canoutput a radiographic image of high quality, which is free from theeffect of scattered rays in the scout image capturing mode, and aradiographic image in the stereographic image capturing mode free of thegrid 48. When the grid 48 is not used, the grid 48 is retracted awayfrom the surface of the solid-state detector 50 by a moving mechanism(not shown) in the image capturing base 52.

FIG. 9 shows an image capturing process for capturing a radiographicimage in the scout image capturing mode together with a radiographicimage in the stereographic image capturing mode with the radiationsource 42 placed in a position E, which is angularly spaced at animaging angle −θ2 (|−θ2|≦30° and |−θ2|>−θ1|) from the position A. At theimaging angle −θ2 (position E), the radiation source 42 is inclined fromthe position A more greatly than in the position C (see FIG. 6).Therefore, if the grid 48 is used in the stereographic image capturingmode, radiation 92 possibly will be removed by the grid 48.Consequently, in position E, the grid 48 is not used in thestereographic image capturing mode. The solid-state detector 50 canoutput a radiographic image of high quality, which is free from theeffect of scattered rays in the scout image capturing mode, and aradiographic image in the stereographic image capturing mode free of thegrid 48.

FIG. 10 shows an image capturing process for capturing radiographicimages in the stereographic image capturing mode, with the radiationsource 42 being placed respectively in positions D and E, which areangularly spaced at the respective imaging angles +θ2, −θ2 from theposition A.

According to this image capturing process, the solid-state detector 50can output two radiographic images in the stereographic image capturingmode free of the grid 48, in the same manner as the image capturingprocesses shown in FIGS. 8 and 9.

FIG. 11 shows in block form the biopsy apparatus 10 according to thepresent embodiment.

As shown in FIG. 11, the biopsy apparatus 10 includes, in addition tothe mechanical components shown in FIGS. 1 through 3, a control systemcomprising an image capturing condition setting section 100, a radiationsource controller 102, a biopsy needle controller 104, a biopsy needlepositional information calculator 106, a compression plate controller108, a detector controller 110, an image information storage 112, a CAD(Computer Aided Diagnosis) processor 114, a display unit 116, a biopsyregion selector 118, a biopsy region positional information calculator120, a travel distance calculator 122, an imaging angle setting section126, and an image capture selector 128. The biopsy needle holdingmechanism 60, the biopsy needle 86, the biopsy needle controller 104,the biopsy needle positional information calculator 106, the biopsyregion selector 118, the biopsy region positional information calculator120, and the travel distance calculator 122 collectively make up abiopsy needle positioning device 130.

The image capturing condition setting section 100 establishes imagecapturing conditions including tube currents, tube voltages, types oftargets and filters to be used in the radiation source 42, doses of theradiation 92, irradiation times, image capturing processes (see FIGS. 4through 10) for the scout image capturing mode and the stereographicimage capturing mode, and image capturing orders. The radiation sourcecontroller 102 controls the radiation source 42 according to the imagecapturing conditions. The biopsy needle controller 104 controls thebiopsy needle holding mechanism 60 in order to move the biopsy needle 86to a desired position. The compression plate controller 108 moves thecompression plate 58 in directions indicated by the arrow z. Thedetector controller 110 controls the solid-state detector 50 to convertthe radiation 92 into a radiographic image, and to store theradiographic image in the image information storage 112.

The biopsy needle positional information calculator 106 calculatespositional information of the tip end of the biopsy needle 86, which hasbeen moved by the biopsy needle controller 104.

The CAD processor 114 processes the radiographic image stored in theimage information storage 112. The display unit 116 displays theprocessed radiographic image.

If the image information storage 112 stores a single radiographic image,then the CAD processor 114 processes the radiographic image so that theradiographic image can be displayed on the display screen of the displayunit 116. If the image information storage 112 stores a singleradiographic image captured in the scout image capturing mode and asingle radiographic image captured in the stereographic image capturingmode, then the CAD processor 114 processes the two respectiveradiographic images so that the two radiographic images cansimultaneously be displayed on the display screen of the display unit116. If the image information storage 112 stores two radiographic imagesboth of which are captured in the stereographic image capturing mode,then the CAD processor 114 processes the two respective radiographicimages so that the two radiographic images can simultaneously bedisplayed on the display screen of the display unit 116.

The display unit 116 displays a single radiographic image processed bythe CAD processor 114 on the display screen, or displays tworadiographic images processed by the CAD processor 114 simultaneously onthe display screen.

The biopsy region selector 118 comprises a pointing device such as amouse or the like. Using the pointing device of the biopsy regionselector 118, a doctor or technician who has viewed a radiographic imageor images on the display unit 116 can select a biopsy region 88 fromwhich tissue is to be sampled, from among a plurality of biopsy regions88 included within the displayed radiographic image. If two radiographicimages are displayed on the display unit 116, then the doctor ortechnician selects a biopsy region 88 in one of the displayedradiographic images, and also selects a biopsy region 88 in the otherdisplayed radiographic image, which corresponds to the biopsy region 88in the one radiographic image.

The biopsy region positional information calculator 120 calculates thethree-dimensional position of the biopsy region 88 based on the positionof the biopsy region 88 in the two radiographic images, which has beenselected with the biopsy region selector 118. The three-dimensionalposition of the biopsy region 88 may be calculated according to a knownmethod of calculating a three-dimensional position in a stereographicimage capturing mode (e.g., the method disclosed in U.S. PatentApplication Publication No. 2004/0171933).

The travel distance calculator 122 calculates a distance that the biopsyneedle 86 is intended to travel with respect to the biopsy region 88,based on the three-dimensional position of the biopsy region 88 ascalculated by the biopsy region positional information calculator 120,and the position of the tip end of the biopsy needle 86 as calculated bythe biopsy needle positional information calculator 106. The biopsyneedle controller 104 moves the biopsy needle 86 based on the distancecalculated by the travel distance calculator 122, so as to sample tissuefrom the biopsy region 88.

The imaging angle setting section 126 comprises a pointing device suchas a mouse or a keyboard. The doctor or technician sets an imaging anglefor the stereographic image capturing mode to a desired angle, in arange from −θ1 to +θ1 or from −θ2 to +θ2 as shown in FIGS. 4 through 10,using the pointing device or the keyboard of the imaging angle settingsection 126. The imaging angle for the stereographic image capturingmode, which has been set in advance by the image capturing conditionsetting section 100, is changed to the imaging angle set via the imagingangle setting section 126.

The image capture selector 128 comprises a pointing device such as amouse or a keyboard. The doctor or technician changes the imagingprocess, which has been set in advance by the image capturing conditionsetting section 100, to another imaging process using the pointingdevice or the keyboard of the image capture selector 128. Even after animage capturing process is performed, the doctor or technician canselect a radiographic image to be used for calculating athree-dimensional position with the biopsy region positional informationcalculator 120, using the pointing device or the keyboard of the imagecapture selector 128.

The biopsy apparatus 10 according to the present embodiment basically isconstructed as described above. Operation of the biopsy apparatus 10will be described below with reference to the flowchart shown in FIG.12.

In step S1, as shown in FIG. 12, image capturing conditions including atube current, a tube voltage, a dose of the radiation 92, an irradiationtime, an imaging angle, an image capturing process, and an imagecapturing order are established using the image capturing conditionsetting section 100 (see FIG. 11). The established image capturingconditions are set in the radiation source controller 102.Alternatively, the imaging angle setting section 126 may establish theimaging angle, and the image capture selector 128 may establish theimage capturing process. Then, the technician securely positions theexaminee 12 in a position lying on the top plate 22 of the bed 14, withthe breast 26 hanging down through the opening 28.

In step S2, the technician positions the breast 26. More specifically,the technician places the breast 26 against the image capturing base 52at a given position, and then the compression plate controller 108 movesthe compression plate 58 toward the image capturing base 52 in thedirection indicated by the arrow z, thereby compressing and positioningthe breast 26.

In step S3, after the breast 26 has been positioned, the radiationsource 42 is energized to capture a radiographic image of the breast 26in the scout image capturing mode. At this time, scattered rays ofradiation 92, which are produced by the breast 26, are removed by thegrid 48, and radiation 92 that has passed through the breast 26 isdetected by the solid-state detector 50 as representing a radiographicimage. The detector controller 110 controls the solid-state detector 50in order to acquire the radiographic image, and temporarily stores theacquired radiographic image in the image information storage 112. TheCAD processor 114 processes the radiographic image stored in the imageinformation storage 112, and displays the processed radiographic imageon the display unit 116. The doctor can confirm that the breast 26,including the biopsy region 88, has been properly positioned in thecaptured area of the radiographic image.

Then, in step S4, the radiation source 42 is energized again in order tocapture a radiographic image of the breast 26 in the stereographic imagecapturing mode. At this time, the stereographic image capturing mode isperformed according to either one of the image capturing processes shownin FIGS. 5 through 10. According to the image capturing process shown inFIG. 5, 6, 8 or 9, a single radiographic image is captured in thestereographic image capturing mode, whereas according to the imagecapturing process shown in FIG. 7 or 10, two radiographic images arecaptured in the stereographic image capturing mode.

In step S4, if a single radiographic image is captured in thestereographic image capturing mode, then the single radiographic imageis stored in the image information storage 112. In step S4, if tworadiographic images are captured in the stereographic image capturingmode, then the two radiographic images are stored in the imageinformation storage 112. Since the number of radiographic imagescaptured according to the image capturing process shown in FIG. 5, 6, 8or 9 is smaller than the number of radiographic images capturedaccording to the image capturing process shown in FIG. 7 or 10, the timerequired to move the radiation source 42 is shorter, and hence theexamination time also is shorter according to the image capturingprocess shown in FIG. 5, 6, 8 or 9.

The CAD processor 114 processes the two radiographic images stored inthe image information storage 112, i.e., two radiographic imagescaptured respectively in the scout image capturing mode and in thestereographic image capturing mode, or two radiographic images both ofwhich are captured in the stereographic image capturing mode, andsimultaneously displays the two processed radiographic images on thedisplay unit 116.

In step S5, the doctor or technician who has viewed the radiographicimages displayed on the display unit 116 operates the biopsy regionselector 118, in order to select a desired biopsy region 88 from whichtissue is to be sampled, from among a plurality of biopsy regionsincluded within the two displayed radiographic images. The biopsy regionpositional information calculator 120 then calculates thethree-dimensional position of the selected biopsy region 88, anddisplays the calculated three-dimensional position on the display unit116.

In step S6, the doctor or technician sterilizes and gives localanesthesia to the breast 26 before piercing the breast 26 with thebiopsy needle 86.

The position of the biopsy region 88 possibly may be moved as a resultof local anesthesia given to the breast 26 in step S6. Therefore, thestereographic image capturing mode is performed according to one of theimage capturing processes shown in FIGS. 5 through 10. The imageinformation storage 112 then stores two radiographic images, while theCAD processor 114 processes the radiographic images stored in the imageinformation storage 112 and displays the processed radiographic image onthe display unit 116. The doctor or technician, having viewed theradiographic images displayed on the display unit 116, operates thebiopsy region selector 118 and again selects a desired biopsy regionfrom which tissue is to be sampled, from among a plurality of biopsyregions included within the two displayed radiographic images. Thebiopsy region positional information calculator 120 then calculates thethree-dimensional position of the selected biopsy region 88, anddisplays the calculated three-dimensional position on the display unit116.

In step S8, the doctor makes an incision in the surface of the breast 26at the position where the biopsy needle 86 is intended to pierce thebreast 26. Thereafter, the biopsy needle 86 is inserted into the breast26 through the incision. The tip end of the biopsy needle 86 moves to aspecified position in the breast 26 in front of the biopsy region 88.

In step S9, the stereographic image capturing mode is performed in thesame manner as in step S7 in order to confirm whether the biopsy needle86 has been inserted in alignment with the biopsy region 88 or not. Thedisplay unit 116 displays the two radiographic images produced in thestereographic image capturing mode. The doctor or technician operatesthe biopsy region selector 118, and again selects a desired biopsyregion 88 from which tissue is to be sampled in the two displayedradiographic images. The biopsy region positional information calculator120 then calculates the three-dimensional position of the selectedbiopsy region 88, displays the calculated three-dimensional position onthe display unit 116, and outputs the calculated three-dimensionalposition to the travel distance calculator 122.

In step S10, the travel distance calculator 122 calculates the distancethat the biopsy needle 86 must travel with respect to the biopsy region88 based on the three-dimensional position of the biopsy region 88 andthe position of the tip end of the biopsy needle 86, which has beencalculated by the biopsy needle positional information calculator 106,and outputs the calculated distance to the biopsy needle controller 104.The biopsy needle controller 104 thus is made capable of moving thesampler 90 of the biopsy needle 86 to the biopsy region 88.

In step S11, the stereographic image capturing mode is carried out inthe same manner as in steps S7 and S9 in order to confirm whether theposition of the biopsy region 88 and the position and direction of thesampler 90 are in agreement with each other. At this time, the displayunit 116 displays two radiographic images produced in the stereographicimage capturing mode, so as to allow the doctor or technician toconfirm, with ease, whether or not the position of the biopsy region 88and the position and direction of the sampler 90 are in agreement witheach other.

In step S12, the holster 80 is actuated to start drawing the biopsyregion 88 and sampling tissue therefrom with the biopsy needle 86.Thereafter, the sampled tissue is examined by an examination apparatus,not shown, to determine whether the tissue is calcified or not, forexample, in step S13.

In step S14, the stereographic image capturing mode is carried out inthe same manner as in steps S7, S9 and S11, in order to confirm whethertissue of the biopsy region 88 has been sampled. At this time, thedisplay unit 116 displays two radiographic images produced in thestereographic image capturing mode in order to allow the doctor ortechnician to confirm, with ease, whether or not the tissue of thebiopsy region 88 has been sampled.

Subsequently, in step S15, the biopsy needle 86 is moved in a reversedirection, as indicated by the arrow z, and is pulled out of the breast26, whereupon the image capturing process is ended.

If all the tissue of the biopsy region 88 has been sampled, the positionof the biopsy region 88 may not need to be confirmed at a later time.Therefore, prior to step S15, in step S16, a stainless steel marker isinserted into the biopsy region 88 through the sampler 90 of the biopsyneedle 86. Thereafter, in step S17, the scout image capturing mode iscarried out in the same manner as in step S3 in order to confirm whetherthe marker has been properly inserted. At this time, the display unit116 displays a radiographic image produced in the scout image capturingmode, so as to allow the doctor or technician to confirm, with ease,whether or not the marker has been properly inserted. Step S15 isexecuted after insertion of the marker has been confirmed.

According to the present embodiment, as described above, since thebiopsy needle 86 is held obliquely to the radiation reception surface ofthe solid-state detector 50, the biopsy needle 86 is reliably preventedfrom overlapping the biopsy region 88 in the radiographic image producedin the scout image capturing mode. Therefore, the radiographic imageproduced in the scout image capturing mode can be used as a radiographicimage for identifying the three-dimensional position of the biopsyregion 88. In other words, the three-dimensional position of the biopsyregion 88 can be identified using two radiographic images producedrespectively in the scout image capturing mode and in the stereographicimage capturing mode.

For identifying the position of the biopsy region 88, it heretofore hasbeen customary to perform the scout image capturing mode, confirm thatthe breast 26 is included in the radiographic image produced in thescout image capturing mode, thereafter move the radiation source 42 fromthe imaging angle used during the scout image capturing mode, thencapture a first radiographic image in the stereographic image capturingmode, move the radiation source 42 again from the imaging angle usedduring the stereographic image capturing mode, capture a secondradiographic image in the stereographic image capturing mode, andsubsequently identify the three-dimensional position of the biopsyregion 88 using the two radiographic images produced in thestereographic image capturing mode. Since it takes time to move theradiation source 42 between image capturing modes, the examining timebecomes prolonged and cannot be shortened.

According to the present embodiment, as described above, since theradiographic image produced in the scout image capturing mode also isused as a radiographic image for identifying the three-dimensionalposition of the biopsy region 88, a second radiographic image, whichheretofore has been produced in the stereographic image capturing modeis no longer required. Rather, in steps S3 and S4, the three-dimensionalposition of the biopsy region 88 can be identified using theradiographic image produced in the scout image capturing mode and thefirst radiographic image produced in the stereographic image capturingmode. As a result, the number of captured radiographic images can bereduced, and hence the dose of radiation 92 applied to the breast 26 isreduced. Further, inasmuch as the number of captured radiographic imagesis reduced, the time required to move the radiation source 42 betweenimage capturing modes can be shortened. Therefore, the time required toexamine the biopsy region 88 is shortened, and the breast 26 isprevented from being held for a long period of time.

Furthermore, since the grid 48 is used in the scout image capturingmode, the radiographic image produced in the scout image capturing modeis of higher quality than the radiographic image produced in thestereographic image capturing mode. Accordingly, a radiographic image ofhigh quality can be used to identify the three-dimensional position ofthe biopsy region 88. In other words, the three-dimensional position ofthe biopsy region 88 can be identified with high accuracy using theradiographic image of high quality and the first radiographic imageproduced in the stereographic image capturing mode.

According to the present embodiment, since two radiographic images canbe produced in the stereographic image capturing mode, in addition totwo radiographic images produced in the scout image capturing mode andthe stereographic image capturing mode, the present embodiment caneasily be applied to existing biopsy apparatus.

Even when two radiographic images are produced in the stereographicimage capturing mode, since the grid 48 is used in acquiring at leastone of the radiographic images with the radiation source 42 being at animaging angle +θ1 (≦+10°) or at an imaging angle −θ1 (|−θ1|≦10°), thethree-dimensional position of the biopsy region 88 can be identifiedusing radiographic images of high quality.

Since the three-dimensional position of the biopsy region 88 can beidentified highly accurately using a radiographic image captured throughuse of the grid 48, a calcified region, which appears pale and vague inthe radiographic images, and which represents a feature of breast cancerat an early stage, can be detected and visually recognized with ease.

Even when the radiation source 42 is at an imaging angle +θ2 (≦+30°) orat an imaging angle −θ2 (|−θ2|≦30°), the three-dimensional position ofthe biopsy region 88 can reliably be identified using radiographicimages produced in the stereographic image capturing mode.

With the biopsy needle 86 being held in an angular range of 0°<φ≦10°,the biopsy needle 86 is prevented from reaching the chest wall 24.

In the present embodiment, the imaging angle setting section 126 can setthe imaging angle +θ1, −θ1, +θ2, −θ2 to any desired angles. The imagecapture selector 128 can select, in advance, two radiographic images tobe produced in the scout image capturing mode and the stereographicimage capturing mode, or two radiographic images to be produced in thestereographic image capturing mode. Furthermore, when the radiographicimage capturing apparatus has captured a plurality of radiographicimages, the image capture selector 128 can select two radiographicimages produced in the scout image capturing mode and the stereographicimage capturing mode, or two radiographic images produced in thestereographic image capturing mode, as the two radiographic images.

Inasmuch as the doctor or technician can set the imaging angles +θ1,−θ1, +θ2, −θ2 to any desired angles, and also can select tworadiographic images to be used to identify the three-dimensionalposition of the biopsy region 88, the image capturing process can beselected depending on the skill of the doctor or technician, therebyresulting in a further reduction in examining time.

In the above embodiment, the examinee 12 lies on the bed 14 when tissueis sampled from the biopsy region 88. However, the principles of thepresent invention also can be applied to an upright biopsy apparatus,which samples a tissue in the biopsy region 88 when the examinee 12 isseated on a chair.

Although a preferred embodiment of the present invention has been shownand described in detail above, it should be understood that variouschanges and modifications may be made to the embodiment withoutdeparting from the scope of the invention as set forth in the appendedclaims.

What is claimed is:
 1. A biopsy apparatus comprising: a radiographicimage capturing apparatus including a radiation source for applyingradiation to a breast of a subject, a radiation detector for detectingthe radiation which has passed through the breast and converting thedetected radiation into a radiographic image, and a radiation sourcedisplacing mechanism for displacing the radiation source relative to theradiation detector; and a biopsy needle positioning device including abiopsy region positional information calculator for calculating athree-dimensional position of a biopsy region of the breast based on atleast two radiographic images obtained by irradiating the breast withthe radiation from directions that are different from each other, abiopsy needle for piercing the biopsy region based on the calculatedthree-dimensional position of the biopsy region and sampling tissue ofthe biopsy region, and a biopsy needle holding mechanism for holding thebiopsy needle, wherein the biopsy needle faces a radiation receptionsurface of the radiation detector, and at least in a scout imagecapturing mode in which the breast is irradiated with the radiationapplied from the radiation source disposed on an axis perpendicular tothe radiation reception surface by the radiation source displacingmechanism, the biopsy needle is held obliquely to the perpendicular axisand the radiation reception surface by the biopsy needle holdingmechanism, wherein one of the at least two radiographic images comprisesa radiographic image produced according to the scout image capturingmode, and wherein the other of the at least two radiographic imagescomprises a radiographic image produced according to the stereographicimage capturing mode, in which the breast is irradiated with theradiation applied from the radiation source, which is disposed obliquelyto the perpendicular axis by the radiation source displacing mechanism.2. A biopsy apparatus according to claim 1, wherein the radiographicimage capturing apparatus further includes a grid for removing scatteredrays of the radiation which are produced by the breast, wherein the gridis used either in both the scout image capturing mode and thestereographic image capturing mode or in only the scout image capturingmode.
 3. A biopsy apparatus according to claim 2, wherein when the gridis used in the stereographic image capturing mode, the radiation sourcehas an imaging angle, which is equal to or smaller than 10° with respectto the axis in the stereographic image capturing mode.
 4. A biopsyapparatus according to claim 1, wherein the radiation source has animaging angle, which is equal to or smaller than 30° with respect to theaxis in the stereographic image capturing mode.
 5. A biopsy apparatusaccording to claim 4, wherein the radiographic image capturing apparatusfurther includes an imaging angle setting section for setting theimaging angle to an angle which is equal to or smaller than 30° withrespect to the axis.
 6. A biopsy apparatus according to claim 1, whereinthe biopsy needle holding mechanism holds the biopsy needle at an angleequal to or smaller than 10° with respect to the axis.
 7. A biopsyapparatus according to claim 1, wherein the radiographic image capturingapparatus further includes an image capture selector for selecting inadvance either the two radiographic images to be produced respectivelyin the scout image capturing mode and the stereographic image capturingmode.
 8. A biopsy apparatus according to claim 1, wherein theradiographic image capturing apparatus further includes an image captureselector for selecting, when the radiographic image capturing apparatushas captured a plurality of radiographic images, radiographic imagesproduced respectively in the scout image capturing mode and thestereographic image capturing mode, as the two radiographic images.
 9. Abiopsy apparatus according to claim 1, wherein the radiographic imagecapturing apparatus comprises a breast image capturing apparatus furtherincluding an image capturing base for holding the breast, the imagecapturing base housing the radiation detector therein, and a compressionplate displaceable toward the image capturing base for compressing thebreast against the image capturing base; and the compression plate hasan opening defined therein through which the biopsy needle can piercethe breast.
 10. A biopsy apparatus according to claim 1, wherein thebiopsy needle is held obliquely to a plane which the perpendicular axispasses through, and on which the radiation source is rotated on aboutthe perpendicular axis by the radiation source displacing mechanism. 11.A biopsy apparatus according to claim 10, wherein the biopsy needle isheld obliquely to the radiation reception surface and the plane in thescout image capturing mode and the stereographic image capturing mode.12. A biopsy apparatus according to claim 1, wherein the biopsy needleis held obliquely to the perpendicular axis and the radiation receptionsurface at such an angle that a tip end of the biopsy needle pointstoward a chest wall of the subject in a plane perpendicular to the chestwall of the subject.
 13. A biopsy method comprising the steps of:detecting radiation applied from a radiation source and having passedthrough a breast of a subject, and converting the detected radiationinto at least two radiation images with a radiation detector having aradiation reception surface, the two radiation images being producedaccording to a scout image capturing mode, in which the breast isirradiated with the radiation applied from the radiation source, whichis disposed on an axis perpendicular to the radiation reception surfaceby a radiation source displacing mechanism, and a stereographic imagecapturing mode, in which the breast is irradiated with the radiationapplied from the radiation source, which is disposed obliquely to theaxis by the radiation source displacing mechanism; calculating athree-dimensional position of a biopsy region of the breast based on theat least two radiographic images with a biopsy region positionalinformation calculator; and piercing the biopsy region with a biopsyneedle based on the calculated three-dimensional position of the biopsyregion and sampling tissue of the biopsy region while the biopsy needlefaces the radiation reception surface and is held obliquely to theradiation reception surface by a biopsy needle holding mechanism,wherein the biopsy needle is held obliquely to the perpendicular axisand the radiation reception surface by the biopsy needle holdingmechanism at least in the scout image capturing mode.